In cellular networks, allocation of radio resources to a certain user equipment (UE), also referred to as scheduling, is typically accomplished dynamically on the network side. In the downlink (DL) direction from the cellular network to the UE, a network node may allocate radio resources in accordance with a need to transmit DL data to the UE. The network node may then inform the UE about the allocated resources by sending a DL assignment. For the uplink (UL) direction from the UE to the cellular network, a scheduling request which is sent by the UE to the cellular network may be used to indicate that the UE needs radio resources for sending UL data. An exemplary scenario based on the LTE (Long Term Evolution) radio access technology specified by 3GPP (3rd Generation Partnership Project) is illustrated in FIG. 1. To provide fast scheduling, a base station of the LTE radio access technology, referred to as “evolved Node B” (eNB) is responsible for the scheduling. This may be accomplished dynamically, taking into account the instantaneous traffic pattern and radio propagation characteristics of each UE.
As illustrated in FIG. 1, a UE 10 which needs to send UL data may first send a scheduling request 101 to an eNB 100 which serves the cell of the UE 10. The scheduling request 101 may be sent on a UL control channel, referred to as PUCCH (Physical Uplink Control Channel), providing dedicated resources for sending scheduling requests by the UE 10. Alternatively, the scheduling request 101 may be sent on a contention based random access channel (RACH). At step 102, the eNB 100 allocates UL radio resources to the UE 10. The amount of allocated resources may vary from between different scheduling transactions. The allocated UL radio resources are indicated in an UL grant 103, which is sent from the eNB 100 to the UE 10. Using the allocated UL radio resources, the UE 10 may then send the UL data 104 to the eNB 100. In addition, the UE 10 may also send a buffer status report indicating the amount of buffered UL data to be sent by the UE 10.
In the above process of transmitting the UL data 104, a delay occurs which is due to the sending of the scheduling request 101 before the UE 10 can proceed with the transmission of the UL data 104. However, such delay is not desirable in many cases. For example, certain data traffic may be sensitive to delay, such as data traffic associated with online gaming or the like.
To address such undesirable delays, it is known to use concepts of blind scheduling, in which UL radio resources are allocated to a UE without prior knowledge whether the UE has UL data to transmit or not. Such blind scheduling is for example described in WO 2011/162502 A2. Generally, blind scheduling of a UE suffers from the risk of wasting of radio resources which are allocated, but not needed by the UE. This may specifically be relevant in high-load situations, where the amount of available UL resources is scarce.
Accordingly, there is a need for techniques which allow for efficiently controlling radio transmissions in a cellular network, in particular with respect to the scheduling of UL transmissions.